Strip bonded roll heater



Aug. 18,1970 -w A,oRR 3,524,967

STRIP BONDED ROLL HEATER Filed June 14, 1968 INVENTOR. WALTON A. ORR

United States Patent 01 Bee 3,524,967 Patented Aug. 18, 1970 U.S. Cl. 219-469 3 Claims ABSTRACT OF THE DISCLOSURE A heater element for heating synthetic fibers having a ceramic body containing a continuous helical groove about its exterior cylindrical surface. An electrical heating element attached at both ends to power supply terminals is wound within the helical groove and is retained therein by a series of equally spaced strips of heat resistant cement traversing the helical groove and embedding the heating element therein.

BACKGROUND OF THE INVENTION In the manufacture of synthetic fibers the fiber must be heated to a predetermined temperature and drawn to the desired thickness before further processing such as weaving, etc. can take place. The heating may be performed by a Roll heater where the surface which contacts the synthetic fibers rotates with the fiber as heat is transferred thereto. To heat this rotating surface a stationary or rotating heater element connected to a suitable power source is suspended within a rotating metal drum which provides the heating surface. Heat from the heating element is transferred to the metal drum by radiation and convection and from there to the fiber by conduction. The heater usually consists of a resistance element Wire wound on a body made of an electrically insulating heat resistance material, such as ceramic. Great care must be taken that the element does not at any time touch the rotating drum causing an eletcrical short circuit. To this effect grooves are provided in the ceramic body to retain the element wire below the exterior surface of the ceramic body. However, when the heating element is energized the element wire produces heat; and, as a consequence thereof, expands in proportion to the heat. The filament wire tends to sag due to this expansion and expanded filament wire is then distributed to the underside of the ceramic body due to gravitational forces. This condition has in the past generally been solved by filling the grooves entirely with a heat resistance cement thereby confining the element wire within the helical groove. This results in considerable strain on the ceramic body due to the unlike amount of expansion and contraction between the filament wire and the ceramic body, thereby causing the ceramic body to crack due to the stress of the expanding wire so that its pieces may move with the expanding element wire as it contracts and expands. Eventually the ceramic body disintegrates and necessitates replacement of the entire heating element.

BRIEF SUMMARY OF THE INVENTION The invention is directed to a construction of a synthetic fiber heater having a cylindrical ceramic body wherein a helical groove is provided in its exterior cylindrical surface for the retention of a heater element. Each end of the heater element is attached to a terminal point located on the ceramic body and the heater element is further confined within the helical groove by a series of evenly spaced strips of cement, allowing expansion of the heating element to occur between the cement strips in evenly distributed segments without placing the cylindrical ceramic body under strain.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an oblique view of the ceramic body having the heating element wound in a groove provided therefor in the exterior surface of the ceramic body.

FIG. 2 is a cross-sectional view showing the heating element placed in grooves provided therefor in the exterior surface of ceramic body.

DETAILED DESCRIPTION Referring now to FIGS. 1 and 2 a cylindrical ceramic body 11 having one open end 13 and a closed end 15 oppositely located thereof which is provided with a plurality of openings 17 for attachment of the ceramic body to a support means (not shown). Reinforcing ribs 19-24 protruding from the interior cylindrical surface 25 of the ceramic body 11 provide increased structral strength to the body. The ceramic bodys exterior cylindrical surface 31 is provided with a continuous, helical groove 33 ending in notched portions 35 located at the open end 13 of body 11 and a similar notch in the closed end 15 (not shown). The continuous helical groove 33 may be uniformly distributed across the surface of the ceramic body or the helix may be closer spaced at the end of the groove as compared to the spacing in the central portion. In the electrical heating element 32 wound tightly within the helical groove 33, when connected to a power source (not shown) will provide heat in proportion to the distribution of the helix in the exterior surface 31 of the ceramic body 11. The notches at either end of the helical groove contain connection terminals through which the heating element 32 is connected to the supply source. The connection terminals also tend to confine the movement of the heating element within the groove 33. To place further restraint on the heating element, a series of evenly spaced strips of cement 27-29 are placed in the groove 33 thereby embedding at predetermined intervals the heating element 32. When the heating element is energized and as a consequence thereof heating occurs, expansion occurs in the heating element wire 32, causing buckling of the wire in the segments between the cemented points. The extent of the buckling depends on the temperature of the heating element causing a proportional amount of expansion, the diameter of the ceramic body 11, and the number of cemented strips retaining the element wire within the grooves. In addition to these values, the calculation for determining the depth of the helical groove 33 must consider the diameter of the wire so that protrusion of the heating element 32 above the cylindrical exterior surface 31 of the ceramic body 11 does not occur when the element is energized. The depth of the groove 33 should be such that heating element 32 is as close to the surface 31 of the ceramic body 11 as possible Without protruding beyond the surface 31 when the element is energized. The ceramic body 11 when used for synthetic fiber heating is stationarily mounted within a rotating metallic drum (not shown). The efliciency of the heater is inversely proportional to the air gap between the heating element and the interior surface of the rotating metallic drum. The groove 33 should, however, be deep enough so that the heating element will not protrude beyond the cylindrical surface 31 and contact the internal surface of the drum whereby an electrical short circuit would be caused.

While the invention has been explained and described with the aid of particular embodiments thereof, it will be understood that the invention is not limited thereby and that many modfications retaining and utilizing the spirit thereof wthout departing essentially therefrom will occur to those skilled in the art in applying the invention to specific operating environments and conditions. It is therefore contemplated by the appended claims to cover all such modifications as fall within the scope and spirit of the invention.

3 4 What is claimed is: References Cited 1. A heater element comprising: I P (a) a heat resistant electrically insulating body havlng grooves in its exterior surface, said grooves having 1, 91,194 4/1924 Burger 338218 a predetermined depth; 5 2,280,977 4/1942 Re chmann 338-270 (b) a heater element wire wound within said grooves; fi llvg slanflluun and ac ona eta. (c) a series of spaced cement strips transversing each 8 ,1 11/1966' Hyde 338303 of said grooves for rigidly securing said heater ele- 3,263,198 7/ 1966 Rothvveller 338303 ment wire at a predetermined depth within said 10 9,2 2 19 8 BOldndge 219470 grooves. 2. The invention claimed in claim 1 wherein said BERNARD GILHEANY: 'Y Examlnel grooves comprise a continuous helix. E LL Assistant Examiner 3. The invention claimed in claim 2 wherein the depth of the groove is an inverse function of the number of ce- 15 U.S. Cl. X.R.

ment strips. 338218, 303 

